Davao, Philippines ? Three countries warned Friday against traveling to the Philippines as police searched for suspects in a bombing that killed 16 people in a southern port city.

President Gloria Macapagal Arroyo also canceled her birthday party and announced a reward for information about the blast.

The bomb went off Wednesday on a bustling wharf in Davao. Two of the dead were children. More than 50 people were wounded.

It was the second attack in Davao in less than a month. On March 4 a bomb went off at the airport, killing 21 people, including a U.S. missionary.

Police have released sketches of two suspects but no one is yet in custody, prompting Australia, Britain and Canada to warn of the possibility of further attacks.

The advisories also warned that travelers to Asia face risks from the Iraqi war, which may cause regional tension, and the outbreak of severe acute respiratory syndrome, or SARS.

“We believe there is a greater risk of terrorist activity throughout the Philippines at the present time,” Britain’s travel advisory said.

Australia said, “Further bomb explosions are possible across the country, including Manila,” and risks are high in airports and seaports.

In Manila, presidential spokesman Ignacio Bunye said Arroyo would forgo her 56th birthday celebration today and put the money she would have spent on catering toward the government’s $18,700 reward.